Optimal Design of Emergency Load Shedding Control for Enhancement of Transient Voltage Security

The differential and algebraic equations (DAE) of power systems which describe transient voltage security problem is established. Representation of load shedding is deduced in terms of the three order induction motor paralleled with constant impedance load model. The optimization model of emergency load shedding control of transient voltage security (ELSCTVS) is presented in which transient voltage security constraints include the constraint avoiding transient voltage instability and avoiding transient delayed voltage recovery, the objective is to minimize load shedding cost. Based on trajectory sensitivities, the approximate linear relationship between transient voltage security constraint functions and control variables is found, and hence this optimization model is transformed into a static linear integer programming model. A heuristic optimal algorithm is used to obtain its solution. Computational results on IEEE 39 bus system demonstrate correctness and effectiveness of the proposed method.